Add getenv() wrapper that works on multibyte environment variable.

On Windows, character encoding of multibyte environment variable varies
depending on settings. The only reliable way to handle it I think is to use
GetEnvironmentVariableW().

GetEnvironmentVariableW() works on wchar_t string, which is on Windows UTF16
string. That's not ideal because we use UTF-8 as the internal encoding in LLVM.
This patch defines a wrapper function which takes and returns UTF-8 string for
GetEnvironmentVariableW().

The wrapper function does not do any conversion and just forwards the argument
to getenv() on Unix.

Differential Revision: http://llvm-reviews.chandlerc.com/D1612

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190423 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 0 deletions

diff --git a/include/llvm/Support/Process.h b/include/llvm/Support/Process.h
index a23c4add42..6d6add0f3e 100644
--- a/include/llvm/Support/Process.h
+++ b/include/llvm/Support/Process.h
@@ -25,11 +25,14 @@
 #ifndef LLVM_SUPPORT_PROCESS_H
 #define LLVM_SUPPORT_PROCESS_H
 
+#include "llvm/ADT/Optional.h"
 #include "llvm/Config/llvm-config.h"
 #include "llvm/Support/DataTypes.h"
 #include "llvm/Support/TimeValue.h"
 
 namespace llvm {
+class StringRef;
+
 namespace sys {
 
 class self_process;
@@ -161,6 +164,10 @@ public:
   /// @brief Prevent core file generation.
   static void PreventCoreFiles();
 
+  // This function returns the environment variable \arg name's value as a UTF-8
+  // string. \arg Name is assumed to be in UTF-8 encoding too.
+  static Optional<std::string> GetEnv(StringRef name);
+
   /// This function determines if the standard input is connected directly
   /// to a user's input (keyboard probably), rather than coming from a file
   /// or pipe.